CODEWITHSUNDEEP
arraysvisual-c++visual-studio-2012
user3394578
user3394578

Reputation: 17

data pointer to std::vector

I am getting an exception with the following code snippet:

//      matlab mex program ...
float *ptr=new float[n*m];
.
.
.
std::vector<float> v(n*m);
v.assign(ptr);

How do I correctly assign ptr to the vector v?

Upvotes: 0

Views: 55

Answers (1)

ltjax
ltjax

Reputation: 15997

You can use either the constructor or assign, as you tried. However, you need to pass the length in some way. In the standard library, it's a common idiom to do this by passing the begin and end of a sequence - but those can be bare pointers. Like this:

std::vector<float> v; // Note you do not need the size here
v.assign(ptr, ptr+n*m);

or just:

std::vector<float> v(ptr, ptr+n*m);

It also seems like you have an error in your allocation:

float *ptr=new float[n*m]; // Allocate floats, not pointers to floats

Upvotes: 2

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